油菜抗咪唑啉酮性状的遗传及其应用

以抗咪唑啉酮类除草剂油菜M9选系M9-2、M9-3、M9-11、M9-14和MI CMS (陆奥-五十铃细胞质雄性不育) 恢复系N221、N340、N341为亲本材料配制杂交组合,研究抗性遗传。结果表明,咪唑啉酮抗性为显性性状,由1对核基因控制,抗性基因在F2和BC1群体遵循孟德尔遗传规律。因此,应用杂交、回交等常规育种方法可将抗性基因导入目标品种。     

油菜乙酰乳酸合酶突变体S638N的酶学特性及其对ALS类除草剂的抗性

在对油菜抗咪唑啉酮类除草剂基因Bn ALS1R克隆与功能验证基础上,为比较抗性基因编码的乙酰乳酸合酶突变体S638N酶学特性及其对ALS类除草剂抗性与野生型的差异,构建基因原核表达载体,在大肠杆菌中表达S638N和野生型的重组融合蛋白。SDS-PAGE和Western blot分析表明,S638N和野生型均能表达出约74 k D的特异性重组蛋白。纯化目的蛋白,在不同温度和pH条件下,测定S638N和野生型的酶活性。结果显示,温度和pH对突变酶活性的影响与野生型相同,表现为先升后降,在37℃、pH 7.0条件下催化活性均最高。同时,该突变酶的酶学动力学参数Km和Vmax与野生型没有显著差异,其对3个辅助因子的响应曲线也与野生型类似,缺少其中任何一个辅助因子均使突变酶S638N基本都没有活性。然而,突变酶S638N对IMI类除草剂抗性显著高于野生型,而对Su类除草剂敏感性和野生型相同。因此,突变酶S638N具有对IMI类除草剂的专一抗性,但未改变酶学反应特征。     

Clearfield® rice: Its development,success, and key challenges on a global perspective

Weedy rice (Oryza sativa) is a close relative of domesticated rice and a noxious weed prevalent in rice fields in world regions where rice is grown. Weedy rice management has remained challenging to farmers, mainly due to the weed's physiological and morphological resemblance to rice cultivars. The introduction of Clearfield^® rice provides an alternative solution and an additional tool for integrated weed management. Clearfield^® rice-based programs result in the cleanest rice fields in the southern U.S. However, persistent application of the imidazolinone herbicides (imazethapyr, imazamox, and imazapic) in Clearfield^® rice raises concerns about the possible evolution of resistance to ALS-inhibitor herbicides in weedy rice and the transfer of resistance trait. The risk of resistant weedy rice evolution is much higher in Asia, Latin America, and other tropical regions where there is no winterkill and rice is planted at least twice each year. Herbicide carryover to rotational crops is also a concern. We summarized the progress of commercialization of Clearfield^® rice in 15 countries across the continents of America, Asia and Europe. In some countries, imidazolinone-resistant weedy rice outcrosses have been found abundant, thereby negating the utility of Clearfield^® technology. The persistence of imidazolinone herbicide residues in the soil is a concern in regions where multiple crops are planted in a year, or the following year. These challenges should be anticipated by countries that are considering adopting Clearfield^® rice technology. Issues associated with gene escape, resistance evolution in weedy rice, and herbicide carryover to rotational crops remain to be resolved. Research to achieve sustainable solutions for weedy rice management, must be continued and intense educational programs for growers must be sustained.     

咪唑啉酮类除草剂对后茬作物安全性研究初报

1996～ 2 0 0 0年进行了咪唑啉酮类除草剂土壤残留对后茬作物影响的田间小区试验。结果表明 ,金豆 (imazamox,甲氧咪草烟 ) 40、6 0 g/ hm2 (在推荐剂量范围内。有效浓度 ,下同 ) ,施药后 12个月可以安全种植小麦、玉米和白瓜籽 ,2 4个月后可以安全种植油菜、甜菜、白菜、亚麻和马铃薯 ;金豆高剂量 (80、 12 0 g/ hm2 )对敏感作物有一定的药害。金普施特(imazethapyr/ imazamox) 50 g/ hm2 (推荐剂量 ) ,施药后 12个月可安全种植小麦、玉米 ,2 4个月可安全种植油菜、白瓜籽和马铃薯 ,不可种植甜菜、白菜和亚麻 ;倍量 (10 0 g/ hm2 )可使敏感作物严重受害。普施特 (imazethapyr) 75g/ hm2 (推荐剂量 ) ,施药后 12个月可安全种植小麦和玉米 ,2 4个月可安全种植白瓜籽和马铃薯 ;2 4个月后仍对油菜、甜菜、白菜和亚麻有严重药害。     

Action mechanisms of acetolactate synthase-inhibiting herbicides

Herbicides that target the acetolactate synthase (ALS) are among the most widely used weed control chemicals since their introduction into the marketplace in the early 1980s, including five classes (sulfonylureas, imidazolinones, triazolopyrimidines, pyrimidinylthio (or oxy)-benzoates and sulfonylamino-carbonyltriazolinones). The mechanism researches have progressed unprecedentedly in the last two decades. Primary mode of action of the ALS-inhibiting herbicides that interfere with the activity of ALS enzyme seems no longer in doubt. Three lines of investigation from physiology, genetics, molecular and chemical structure aspects came together to prove that ALS is the site of action. Researches on the effects of branched chain amino acids (BCAAs) synthesis or protein metabolism caused by ALS-inhibiting herbicide elicit lots of disputations. Besides these two main works, other secondary effects of ALS inhibition, such as buildup of 2-ketobutyrate (α-ketobutyrate or 2-KB) or 2-aminobutyrate (2-AB, the transamination product of 2-KB), depletion of intermediates of the pathway for some critical processes, disruption of photosynthesis transport and respiration system etc., have also been implicated in the mechanism of plant death. However, there are still some disputations and doubts on the precise mechanisms that need further probing into. Further more, as many ALS-inhibiting herbicides and their derivatives are chiral with one or even more enantiomers, which may behave quite differently in biochemical processes, the effects and the environmental fate of chiral herbicides need to be investigated stereospecifically. By this, we can have a better understanding about the herbicides and avoid unnecessary pollution load.     

油菜抗咪唑啉酮类除草剂基因BnALS1R等位基因特异PCR标记的开发与应用

油菜抗咪唑啉酮类除草剂基因BnALS1R是从抗性突变体M9中克隆获得,抗性基因BnALS1R与野生型基因BnALS1存在1处SNP,即乙酰乳酸合酶第638位丝氨酸残基被天冬酰胺酸替代。为获得油菜抗除草剂基因BnALS1R的分子标记,根据该处点突变,结合获得的BnALS3与BnALS1序列,开发30条等位基因特异PCR (allele-specific PCR,AS-PCR)引物,采用筛选出的3条AS-PCR引物在F₂、BC₁和BC₂群体中进行PCR扩增。结果表明,该标记有效检测出群体中存在的3种基因型,其分离比分别为1∶2∶1、1∶1、1∶1,均遵循单基因遗传规律。应用该标记对获得的抗性恢复系进行PCR扩增,结果发现所有抗性恢复系均能扩增出抗性基因BnALS1R目的条带,表明3条标记引物可应用于抗性基因的检测。AS-PCR标记的获得将促进以抗性基因进行油菜抗除草剂分子标记辅助选择育种。